As nasty as the Akismet spam inbox can be, the wp_options table can be just as bad for plugin addicts. Have you ever played around with a shoutbox, poll or bot tracker plugin on your WordPress blog? These types of plugins create a bunch of rows in your wp_options table that stay behind long after you disabled or deleted the plugin.
The only benefit of leaving these rows in your wp_options table is if you decide to reactivate the plugin, its settings are preserved. Otherwise, these rows just hang around and take up space.
There’s no sure fire way to get rid of these rows other than runnign sql queries which require you to know what exactly you are looking for before you delete it. Actually, that’s not a bad practice but not all of us are keen on scrolling through a couple of hundred rows looking for rows which could be associated with the old plugin.
Plugin registration is something that needs to be considered by developers. Since the developers know which rows their plugin created in the wp_options table, they should consider a button on their plugin configuration page which will allow the user to efficiently delete their rows as a part of the deactivation process.